Apple is expected to announce plans in a few days to make its Siri voice assistant work with a larger variety of apps, as the technology company looks to counter the runaway success of Amazon.com Inc's competing Alexa service.

However, the Cupertino, California company is likely to stick to its tested method of focusing on a small amount of features and trying to perfect them, rather than casting as wide a net as possible, according to engineers and artificial intelligence industry insiders.

Currently, Apple's Siri works with only six types of app: ride-hailing and sharing; messaging and calling; photo search; payments; fitness; and auto infotainment systems. At the company's annual developer conference in a couple of days, it is expected to add to those categories.

Some industry-watchers have also predicted Apple will announce hardware similar to Amazon's Echo device for the home, which has been a hot-seller recently. Apple declined comment.

But even if Siri doubles its areas of expertise, it will be a far cry from the 12,000 or so tasks that Amazon.com's Alexa can handle.

The difference illustrates a strategic divide between the two tech rivals. Apple is betting that customers will not use voice commands without an experience similar to speaking with a human, and so it is limiting what Siri can do in order to make sure it works well.

Amazon puts no such restrictions on Alexa, wagering that the voice assistant with the most "skills," its term for apps on its Echo assistant devices, will gain a loyal following, even if it sometimes makes mistakes and takes more effort to use.

The clash of approaches is coming to a head as virtual assistants that respond to voice commands become a priority for the leading tech companies, which want to find new ways of engaging customers and make more money from shopping and online services.